| 176 | Second Highest Salary | Database | Medium |
| 177 | Nth Highest Salary | Database | Medium |
| 178 | Rank Scores | Database | Medium |
| 179 | Largest Number | ArrayStringGreedy+1 | Medium |
| 180 | Consecutive Numbers | Database | Medium |
| 184 | Department Highest Salary | Database | Medium |
| 187 | Repeated DNA Sequences | Hash TableStringBit Manipulation+3 | Medium |
| 189 | Rotate Array | ArrayMathTwo Pointers | Medium |
| 192 | Word Frequency | Shell | Medium |
| 194 | Transpose File | Shell | Medium |
| 198 | House Robber | ArrayDynamic Programming | Medium |
| 199 | Binary Tree Right Side View | TreeDepth-First SearchBreadth-First Search+1 | Medium |
| 200 | Number of Islands | ArrayDepth-First SearchBreadth-First Search+2 | Medium |
| 201 | Bitwise AND of Numbers Range | Bit Manipulation | Medium |
| 204 | Count Primes | ArrayMathEnumeration+1 | Medium |
| 207 | Course Schedule | Depth-First SearchBreadth-First SearchGraph+1 | Medium |
| 208 | Implement Trie (Prefix Tree) | Hash TableStringDesign+1 | Medium |
| 209 | Minimum Size Subarray Sum | ArrayBinary SearchSliding Window+1 | Medium |
| 210 | Course Schedule II | Depth-First SearchBreadth-First SearchGraph+1 | Medium |
| 211 | Design Add and Search Words Data Structure | StringDepth-First SearchDesign+1 | Medium |
| 213 | House Robber II | ArrayDynamic Programming | Medium |
| 215 | Kth Largest Element in an Array | ArrayDivide and ConquerSorting+2 | Medium |
| 216 | Combination Sum III | ArrayBacktracking | Medium |
| 221 | Maximal Square | ArrayDynamic ProgrammingMatrix | Medium |
| 223 | Rectangle Area | MathGeometry | Medium |
| 227 | Basic Calculator II | MathStringStack | Medium |
| 229 | Majority Element II | ArrayHash TableSorting+1 | Medium |
| 230 | Kth Smallest Element in a BST | TreeDepth-First SearchBinary Search Tree+1 | Medium |
| 235 | Lowest Common Ancestor of a Binary Search Tree | TreeDepth-First SearchBinary Search Tree+1 | Medium |
| 236 | Lowest Common Ancestor of a Binary Tree | TreeDepth-First SearchBinary Tree | Medium |
| 237 | Delete Node in a Linked List | Linked List | Medium |
| 238 | Product of Array Except Self | ArrayPrefix Sum | Medium |
| 240 | Search a 2D Matrix II | ArrayBinary SearchDivide and Conquer+1 | Medium |
| 241 | Different Ways to Add Parentheses | MathStringDynamic Programming+2 | Medium |
| 260 | Single Number III | ArrayBit Manipulation | Medium |
| 264 | Ugly Number II | Hash TableMathDynamic Programming+1 | Medium |
| 274 | H-Index | ArraySortingCounting Sort | Medium |
| 275 | H-Index II | ArrayBinary Search | Medium |
| 279 | Perfect Squares | MathDynamic ProgrammingBreadth-First Search | Medium |
| 284 | Peeking Iterator | ArrayDesignIterator | Medium |
| 287 | Find the Duplicate Number | ArrayTwo PointersBinary Search+1 | Medium |
| 289 | Game of Life | ArrayMatrixSimulation | Medium |
| 299 | Bulls and Cows | Hash TableStringCounting | Medium |
| 300 | Longest Increasing Subsequence | ArrayBinary SearchDynamic Programming | Medium |
| 304 | Range Sum Query 2D - Immutable | ArrayDesignMatrix+1 | Medium |
| 306 | Additive Number | StringBacktracking | Medium |
| 307 | Range Sum Query - Mutable | ArrayDesignBinary Indexed Tree+1 | Medium |
| 309 | Best Time to Buy and Sell Stock with Cooldown | ArrayDynamic Programming | Medium |
| 310 | Minimum Height Trees | Depth-First SearchBreadth-First SearchGraph+1 | Medium |
| 313 | Super Ugly Number | ArrayMathDynamic Programming | Medium |